Heat control for catalytic heaters

ABSTRACT

The amount of heat produced by a catalytic heater is controlled by exposing more or less of the catalytic surface where combustion takes place. Closely fitting covers are manually movedto cover or expose the catalytic surface and the covers may be slid, rotated or moved in segments or in whole toward or away from the combustion surface. Support structures for the movable covers may extend from the spaced walls of a heat shield. Relative movement between the covers and combustion surface may be accomplished by a stationary combustion surface and movable cover or between a stationary cover and movable combustion surface. The combustion surface is improved by covering with a fine mesh screen.

nited States Patent [191 Gottwald et a].

[4 1 Feb. 18,1975

[ HEAT CONTROL FOR CATALYTIC HEATERS 22 Filed: Oct. 18, 1973 21 Appl. No.: 407,602

Gladden ct a]. 431/329 X Okui 431/329 Primary Examiner-William F. ODea Assistant Examiner-Peter D. Ferguson Attorney, Agent, or Firm-Harry W. Brelsford [5 7] ABSTRACT The amount of heat produced by a catalytic heater is controlled by exposing more or less of the catalytic surface where combustion takes place. Closely fitting covers are manually movedto cover or expose the catalytic surface and the covers may be slid. rotated or moved in segments or in whole toward or away from the combustion surface. Support structures for the movable covers may extend from the spaced walls of a heat shield. Relative movement between the covers and combustion surface may be accomplished by a stationary combustion surface and movable cover or between a stationary cover and movable combustion surface. The combustion surface is improved by covering with a fine mesh screen.

18 Claims, 21 Drawing Figures PATENTEU FEB 1 8 SHEET 10F 3 Y- R. ANH OD mw mm PAH-1min Him 1 81975 SHEET 3 OF 3 HEAT CONTROL FOR CATALYTIC HEATERS This invention relates to the control of catalytic heaters by providing an adjustable mechanism to cover or uncover more or less of the combustion surface where flameless combustion takes place.

Catalytic heaters are widely used by cold weather sportsmen and persons working in the cold, to provide a safe low temperature source of heat free from carbon monoxide fumes. Small pocket size warmers are carried in the sportsmens pocket to warm fingers of the hand and larger bucket-size heaters are used as tent and cabin heaters. Pocket warmers have a perforated heat shield surrounding the burner or combustion surface since this latter becomes hot enough to burn fingers or char the fabric of pockets. The larger tent heaters are usually devoid of a heat shield.

This invention will be described primarily with reference to pocket warmers of the type employing heat shields, but it is equally effective on other types of catalytic heaters.

Heaters of this type generally have a fuel container filled with an absorbent material such as cotton waste. Gasoline, lighter fluid or similar volatile fuel is poured into the container and the fumes of the fuel exit through an outlet mouth, preferably surrounded by lips. A burner formed of non-combustible fibrous material, such as asbestos, is held on the lips of the mouth to intercept the gases and vapors from the fuel. When this fibrous material is dipped in a salt of platinum and heated to form platinum, it becomes catalytic. When a match is applied to the burner, the vapors thereafter burn without a flame and at a temperature considerably below that of flame burners. Furthermore, the combustion is complete and carbon monoxide is not given off.

As the time of burning progresses the burner heats up the fuel container and the vaporization of the fuel increases and the pocket warmer gets hotter and hotter. Frequently it gets uncomfortably hot, but more importantly it uses its fuel more quickly. Generally a steady heat of long duration is desired. Various attempts have been made to regulate the heat output. Some attempts have been made to valve off part of the vapor outlet. Other attempts have been made to restrict the flow of air to the burner. None of these have been successful.

We have discovered that quite accurate and reliable and adjustable control of the heat output of catalytic heaters can be achieved by adjustable covers that fit fairly closely over the burner surface. Apparently the combustion surface is reduced and this in turn reduces the amount of heat generated. We have further found that the heater output may be made extremely steady by covering the surface of the burner with a wire screen of extremely fine mesh.

Various objects, advantages and features of the invention will be apparent in the following description and claims considered together with the drawings forming an integral part of this specification, in which:

FIG. I is an elevation view partly in section of a pocket warmer having a cover embodying the invention.

FIG. 2 is a side view partly in section along the line II-II and partly in full outline.

FIG. 3 is an elevation view of the pocket warmer of FIG. 1.

FIG. 4 is a fragmentary view of a cover over a burner constructed along the general lines of the warmer of 2v FIGS. 1 through 3, but using three parts to the cover rather than two.

FIG. 5 is an elevationview with the heat shield in full section of a warmer wherein the cover is in two parts, each of which moves along the length of the burner.

FIG. 6 is an elevation view, partly in section along the line VIVI of FIG. 5.

FIG. 7 is a fragmentary elevation view of a modified form of sliding cover wherein only one moving part is employed.

FIG. 8 is an elevation view partly in section through the heat shield and through supporting parts of the fuel container showing a stationary cover and showing a movable burner which is moved by means of a friction button on the heat shield.

FIG. 9 is a side view of the burner of FIG. 8 partly in section along the line IX-IX.

FIG. 10 is an elevation view with the heat shield in full section ofa form of the invention wherein the cover moves with a rotary motion.

FIG. 11 is a view partly in section along the line XIXI of FIG. 10 and partly in full outline.

FIG. 12 is a side view of the warmer of FIG. 10 partly in section along the line XII-XII and partly in full outline.

FIG. 13 is a plan view with a section through the heat shield showing a rotary type of motion between the heat shield and the fuel cell for covering a curved burner element.

FIG. 14 is an end view partly in section through the heat shield along the line XIV-XIV showing the attachment of the cover to the rotary heat shield.

FIG. 15 is an elevation view partly in section through the heat shield showing a cover which moves vertically over the burner element.

FIG 16 is an end view of the warmer of FIG. 15 partly in section along the line XVl.--XVI and partly in full outline.

FIG. 17 is an elevation view of a warmer wherein the heat shield is in full section showing a cover that is movable by a sliding action lengthwise of the elongated burner.

FIG. 18 is an end view partly in section along the line XVIII-XVIII of FIG. 17 and partly in full outline showing part of the sliding construction.

FIG. 19 is an end view partly in section along the line XIX--XIX and partly in full outline showing further details of the construction.

FIG. 20 is a three-dimensional view ofa catalytic tent heater wherein a hinged sector type of cover is employed to cover part of the catalytic surface and thereby regulate heat.

FIG. 21 is a fragmentary sectional view on an enlarged scale of a section along the line XXI-XXI of FIG. 20 showing the stacking of sectors which are hinged.

Referring to FIGS. 1 through 3 there is illustrated a catalytic heater of the pocket type having a lower section 26 which is a fuel container and which has an outlet 27 for vapors, preferably surrounded by outwardly protruding lips 28. Disposed on the lips 28 is an elongated cylinder 29 which is the catalytic burner. In accordance with the present invention this burner 29 may be constructed of conventional materials except that its exterior is covered with a fine metal mesh of wires to the inch or smaller, and at present we prefer 200 wires to the inch made of stainless steel.

The fuel container 26 has a step 31 to receive a heat shield 32 carrying the conventional air openings 33 which admit oxygen to the burner 29 to support combustion of the fumes which rise from the fuel container 26. Shown best in FIGS. 2 and 3 the heat shield 32 has a pair of parallel slots 34 along which ride a pair of friction buttons 36 which have a stem 37 supporting a lefthand cover segment 38 and a right-hand cover segment 39 as viewed in FIG. 1.

Each cover 38 and 39 covers approximately half of the elongated burner 29 and the friction buttons 36 may be used to move two covers 38 and 39 individually by pulling downwardly on the buttons. If the left-hand cover 38 is pulled completely downwardly it will closely cover the left-hand side of the burner 29 as viewed in FIG. 1 and thereby reduce its heat output to one-half. Moving the other cover 39 completely downwardly shuts off the burner surface completely so that there is no combustion and no heat output.

Referring to FIG. 4 there is a modification of the structure of FIGS. 1 through 3 in that there are three segments, a left-hand cover 41, a right-hand cover 42, and a gap between them is covered by a third cover 43. As shown in FIG. 4, they are in their complete downward movement where they completely seal off a burner 44. The structure of FIG. 4 has the gap between the segments 41 and 42 sufficiently wide so that combustion will be maintained on that part of the surface of the burner 44 when the segment 43 is elevated. This segment accordingly acts as a pilot light while producing very low heat and with a consequent very low consumption of fuel. When it is desired to increase the heat output one or the other, or both, of the covers 41 and 42 are moved upwardly by a suitable mechanism such as that illustrated in FIGS. 1 through 3.

.Shown in FIGS. and 6 is a modified form of cover wherein the movement is along the direction of elongation of the burner. Accordingly, a fuel container 46 may have an outlet covered by a burner 47 and a heat shield 48 is supported on the fuel container 46. Formed in the top of the heat shield 48 are a pair of slots 50 within which reciprocate a pair of vertical rods 49 having a friction button 51 on the outside of the heat shield and connected on their interior side to a pair of burner covers 52 and 53. The burner covers may telescope if desired, or may abut each other to completely close off the burner 47 when they are moved toward each other. They may be moved varying distances apart from each other to expose any desired amount of the burner 47.

Illustrated in FIG. 7 is a modified form of the burner of FIGS. 5 and 6 wherein a single cover slides in the direction of elongation of the burner. Accordingly, a burner 54 may have an end cap 56 at its left hand and a sliding cover 57 of U-shape construction may move varying distances toward and away from the end cap 56 to expose greater or lesser amounts of the burner 54. A button disposed in the side of the heat shield for the warmer may support the cover 57.

Illustrated in FIGS. 8 and 9 is another pocket warmer wherein the cover is stationary and the burner is moved back and forth into and out of the cover. The fuel container 59 has a vapor outlet 61 having a burner 62 disposed over the outlet in the maximum heat condition of the catalytic heater. Secured to the top of the fuel container 59 is a double groove guide 63 in which slides a valve plate 64 for shutting off various desired portions of the vapor outlet 61. Secured to this valve plate 64 is an end cap 66 which, in turn, supports the burner 62. Projecting from the top of the end cap 66 is a right angle stem 67 which passes through a groove 68 in a heat shield 69 disposed over the fuel container 59. To remove the heat shield 69 for lighting the burner 62 there is provided a vertical slot 71 that communicates with a horizontal slot 68.

The right angle stem 67 terminates in a friction button 72 at its outer end and movement of this button causes the burner 62 to move inwardly and outwardly of a close fitting cover 73 which is stationary and secured to the fuel container 59. As the burner 62 moves to the right, as viewed in FIG. 8, the valve plate 64 covers rather tightly portions of the vapor outlet 61. Not only is the burning surface of the burner 62 reduced by movement to the right into the cover 73, but also the amount of vapor escaping is reduced by closing off the vapor outlet.

Referring to FIGS. 10 through 12 there is illustrated a rotary type of cover for a burner. A fuel container 74 has a vapor outlet 76 over which is disposed a stationary burner 77. Secured to one side of the outlet structure 76 is a semi-circular or semi-cylindrical segment 78 fitting closely to the burner 77. Also secured to the outlet structure 76 is a pair of end caps 79 closing off each end of the burner 77. Disposed over the burner also and on top of the stationary cover 78 is a semicylindrical movable cover 81. Projecting from the top of the cover 81 is a right angle stem 82 which passes through an arcuate slot 83 in the side wall of the heat shield 85, and a friction button 84 is disposed on the outside of the heat shield 85. The part of the supporting stem 82 disposed in the slot itself isenlarged sidewise at 86 to ride in a portion of the slot 83 and to be guided by it to achieve a circular path of motion.

In operating the warmer of FIGS. 10 through 12, as viewed in FIG. 12, the greater portion of the burner 77 will be exposed if the stem 82 is moved to the right. As the stem 82 is moved to the left, as viewed in FIG. 12, then a greater portion of the burner 77 will be covered and the heat output will be reduced.

Referring to FIGS. 13 and 14, a fuel container 88 is generally round in shape and has a vapor outlet (not shown) of arcuate shape over which is disposed an arcuate shaped burner 89. Slidingly fitted on the fuel container 88 is a heat shield 91 having an inwardly depending stem 92 which supports a curved or arcuate cover 93 open on the end towards the burner 89 and closed at the other end. Regulation of heat output is obtained by rotating the heat shield 91 with respect to the fuel container 88 to cause the cover 93 to cover more or less of the exterior area of the burner 89 and thereby reduce or expand its heat output. The cross-sectional shape of the cover 93 may be U-shaped.

Referring to FIGS. 15 and 16 there is illustrated an embodiment of the invention wherein a single cover moves at right angles to the direction of elongation of the burner. A fuel container 94 has a vapor outlet (not shown) over which is disposed a catalytic burner 96. Slidingly connected to the fuel container 94 is a perforated heat shield 97 having a vertical slot 98 therein through which projects a stem 98 terminating in an exterior button 99, and the interior end of the stem 98 supports a one-piece cover 101. The heat output of the burner 96 is regulated by moving the cover 101 downwardly and when about half of the burner is covered there is a reduction in heat, which decreases as the cover 101 is moved toward the fuel container 94. When the cover 101 is all the way down and in tight contact with the fuel container 94, not only is the combustion of the burner completely out, but it restrains normal va pors from escaping from the fuel container 94, thus preserving the fuel for future use.

Referring to FIGS. 17 through 19 there is illustrated a type of cover wherein a multi-part cover slides lengthwise of the burner element. A fuel container 102 has a vapor outlet 103 over which is disposed a burner 104. Covering the burner 104 is a two-piece cover 106 and 107. The covers 106 and 107 are preferably of generally semicylindrical construction, except that one end has an end cap 106a and 107a respectively, so that when the covers enclose the burner, as shown in FIG. 17, the ends of the burner will also be enclosed. Each cover 106 and 107 is supported by a stem 108 terminating in a friction button 109 on the exterior of a heat shield 111. Slots 112 are formed on each side of the heat shield so that each cover part may be independently movable.

Illustrated in FIGS. 20 and 21 is a tent-type of catalytic heater which has no heat shield. Such heaters are normally extinguished by placing a close-fitting pan over the top of the heater to thereby cut off all flow of oxygen. A fuel container 113 has a top surface 114 which acts as a catalytic burner surface and this surface is covered with a wire screen 116. Hinged to the screen 116 by a hinge pin 117 are a plurality ofthin sheetmetal sectors 118, each of which may terminate at its outer end in a tab 119 which are staggered in location so as to make then independently movable. The output of heat from the tent heater is regulated by a covering more or less of the catalytic surface 114 by moving one or more of the sectors 118 over the surface about the hinge pin 117.

OPERATION All of the embodiments ofthe invention are generally operated in the same fashion to light the catalytic burner, except for FIGS. 20 and 21 where there is no heat shield and the burner is lighted by applying a match to the top surface 14. In all the other embodiments of the invention the heat shield is removed from the fuel container and this exposes the burner in each case. The user then strikes a match and lights the burner, which immediately starts to produce heat without a flame and without production of carbon monoxide. If the fuel container is extremely cold there will be few vapors present in the burner to support combustion and sometimes it is necessary to warm the fuel container by holding it against the body of the user or otherwise applying heat to it. Once the burner is lighted, it produces heat and the amount of heat output is regulated by moving the covers to expose more or less of the burner surface. In FIGS. 1 through 4 this movement is effected bymanually moving the appropriate friction buttons along a vertical line. In FIGS. 5 and 6 friction buttons 51 are moved horizontally from the top of the heat shield. In FIGS. 8 and 9 the slot 68 is horizontal and the friction button 72 is moved horizontally to move more or less of the burner 62 into the stationary cover 73. In FIGS. 10 through 12 the motion is rotary along an arcuate slot and the semicylindrical shield 81 exposes more or less of the burner 77 to regulate the heat output. In FIGS. 13 and 14 the regulation of heat output is obtained by rotating the heat shield 91 with respect to the fuel container 88. In FIGS. 15 and 16 the movement is vertical and the one-piece cover 101 is moved verticallyto cover more or less of the burner 96. In FIGS. 17 through 19 the movement of friction buttons 109 is horizontal to expose more or less of the burner 104. In FIGS. 20 through 21 the area of combustion is reduced by rotating sectors 118 about their pivot point 117 to cover more or less of the catalytic burning area 114.

SPACING OF THE COVER It is desirable to have the covers over the burners as close to the catalytic surface as production tolerances permit. The covers can actually touch the burner if desired, because we have covered it with a strong stainless steel mesh, even though it is extremely fine. In production, however, a spacing of about a sixteenth of an inch has proved to be very effective. Once the cover is moved over an operating burner it stops oxygen from reaching the covered part of the burner and heat output is reduced. For a short time after covering a burner the vapors in that part of the burner will escape unburned, but it quickly cools and the entire heater cools due to the lower output and the vapor output stabilizes along with the amount of exposed burner to give a regulated heat output with little waste of fuel. This spacing of cover to the burner depends, of course. on dimensions and geometry, but a spacing up to one-eighth inch has been found effective on small burners. Spacings greater than this permit convection currents to occur inside the cover. whereby oxygen is carried to the covered part of the burner. Normally, however, in suitable dimensions between burner and cover, the vapor present within the cover excludes oxygen and makes that part of the burner ineffective. The term close-fitting for the cover, as used in this specification, indicate a cover whose spacing is very close to the burner and, in any event, probably not more than one-eighth of an inch for small pocket-types of burners. Covers of the type shown in FIGS. 15 and 16 are especially desirable inasmuch as they completely close off the flow of vapor from the fuel container, thereby prolonging the life. Even when the burner is not being operated there is some loss of fuel due to vaporization in the absence of such a tight-fitting cover. The other covers, of course, can serve this function, depending upon the tightness of the fit of their various parts and effectiveness of the closure when the burner is completely covered. Covering the catalytic burner with the fine mesh screen previously described protects it not only from the soot of matches, but also from abrasion due to manual touching and from contamination by oil and dirt which reduces its effectiveness. Also, the fine screen seems to make it easier to start the burner when igniting it with a match.

Various modifications and variations and improvements will occur to those skilled in the art. For example, the burner could be square or round and the covers have a corresponding shape. The covers may be fixed to the heat shield and the shield moved toward and away from the fuel container to effect regulation. The invention has been described with reference to presently preferred embodiments, but is not limited to these embodiments and all modifications and variations that fall within the true spirit and scope of the invention are included within the appended claims.

We claim: 1

l. A catalytic heater having an adjustable heat output comprising:

a. a fuel container having a vapor outlet;

b. a catalytic burner disposed over the outlet;

c. and a cover fitting closely over the burner that is relatively movable with respect to the burner, whereby greater or lesser portions of the burner surface may be exposed to ambient air for combustion of fuel vapors.

2. An adjustable heater as set forth in claim 1 wherein the burner is stationary and the cover is movable.

3. An adjustable heater as set forth in claim 1 wherein the cover is stationary and the burner is movable.

4. An adjustable heater as set forth in claim 1 wherein the burner is surrounded with a perforated heat shield and the cover is mounted on the heat shield.

5. An adjustable heater as set forth in claim 1 wherein the cover is mounted on the fuel container.

6. An adjustable heater as set forth in claim 1 wherein the cover is in plural parts and the cover parts are independently movable with respect to the burner to cover more or less of the burner surface.

7. An adjustable heater as set forth in claim 1 wherein the burner surface is covered with a metal screen of fine mesh.

8. A heater as set forth in claim 1 wherein a valve is provided for the vapor outlet, and the valve is connected to the movable one of said burner and cover to close off or open up a proportional part of the vapor outlet as the burner is covered or uncovered for heat control.

9. A catalytic heater having an adjustable heat output comprising:

a. a fuel container having a vapor outlet;

b. an elongated catalytic burner disposed over the outlet;

c. a perforated heat shield surrounding the burner;

d. and a close fitting cover supported by the heat shield and movable relative to the burner to cover more or less of the burner surface to regulate the heat output of the burner.

10. A heater as set forth in claim 9 wherein the cover moves at right angles to the direction of elongation of the burner.

11. A heater as set forth in claim 10 wherein the cover is in plural parts and each is independently movable.

12. A heater as set forth in claim 9 wherein the cover has three parts, each independently movable, and two of them placed over the burner leaves a small part of the burner exposed to maintain combustion at that point with low heat, to act as a pilot light for other portions of the burner as they are uncovered, and the third cover portion closes off this pilot light section.

13. A heater as set forth in claim 9 wherein the cover moves lengthwise of the burner.

14. A heater as set forth in claim 9 wherein the cover rotates to expose more or less of the burner surface.

15. A heater as set forth in claim 9 wherein the cover is fixed to the heat shield and the heat shield rotates with respect to the fuel container to thereby cover more or less of the burner.

16. A heater as set forth in claim 9 wherein the heat shield is slotted in the direction of relative movement of the cover and burner and a stem connected to one of said cover and burner projects to the exterior of the shield so as to manually effect relative movement by sliding the button along the slot.

17. A heater as set forth in claim 9 wherein the cover is fixed to the heat shield and the shield moves relative to the fuel container to thereby cover more or less of the burner.

18. In a catalytic heater having a burner surface, the method of regulating the heat output of the heater comprising:

a. excluding oxygen from a selected portion of the burner surface;

b. allowing free access of oxygen to the remaining portion of the burner surface;

c. and varying the amount of surface from which the oxygen is excluded to thereby achieve a desired amount of heat from that part of the burner surface to which the oxygen has free access. 

1. A catalytic heater having an adjustable heat output comprising: a. a fuel container having a vapor outlet; b. a catalytic burner disposed over the outlet; c. and a cover fitting closely over the burner that is relatively movable with respect to the burner, whereby greater or lesser portions of the burner surface may be exposed to ambient air for combustion of fuel vapors.
 2. An adjustable heater as set forth in claim 1 wherein the burner is stationary and the cover is movable.
 3. An adjustable heater as set forth in claim 1 wherein the cover is stationary and the burner is movable.
 4. An adjustable heater as set forth in claim 1 wherein the burner is surrounded with a perforated heat shield and the cover is mounted on the heat shield.
 5. An adjustable heater as set forth in claim 1 wherein the cover is mounted on the fuel container.
 6. An adjustable heater as set forth in claim 1 wherein the cover is in plural parts and the cover parts are independently movable with respect to the burner to cover more or less of the burner surface.
 7. An adjustable heater as set forth in claim 1 wherein the burner surface is covered with a metal screen of fine mesh.
 8. A heater as set forth in claim 1 wherein a valve is provided for the vapor outlet, and the valve is connected to the movable one of said burner and cover to close off or open up a proportional part of the vapor outlet as the burner is covered or uncovered for heat control.
 9. A catalytic heater having an adjustable heat output comprising: a. a fuel container having a vapor outlet; b. an elongated catalytic burner disposed over the outlet; c. a perforated heat shield surrounding the burner; d. and a close fitting cover supported by the heat shield and movable relative to the burner to cover more or less of the burner surface to regulate the heat output of the burner.
 10. A heater as set forth in claim 9 wherein The cover moves at right angles to the direction of elongation of the burner.
 11. A heater as set forth in claim 10 wherein the cover is in plural parts and each is independently movable.
 12. A heater as set forth in claim 9 wherein the cover has three parts, each independently movable, and two of them placed over the burner leaves a small part of the burner exposed to maintain combustion at that point with low heat, to act as a pilot light for other portions of the burner as they are uncovered, and the third cover portion closes off this pilot light section.
 13. A heater as set forth in claim 9 wherein the cover moves lengthwise of the burner.
 14. A heater as set forth in claim 9 wherein the cover rotates to expose more or less of the burner surface.
 15. A heater as set forth in claim 9 wherein the cover is fixed to the heat shield and the heat shield rotates with respect to the fuel container to thereby cover more or less of the burner.
 16. A heater as set forth in claim 9 wherein the heat shield is slotted in the direction of relative movement of the cover and burner and a stem connected to one of said cover and burner projects to the exterior of the shield so as to manually effect relative movement by sliding the button along the slot.
 17. A heater as set forth in claim 9 wherein the cover is fixed to the heat shield and the shield moves relative to the fuel container to thereby cover more or less of the burner.
 18. In a catalytic heater having a burner surface, the method of regulating the heat output of the heater comprising: a. excluding oxygen from a selected portion of the burner surface; b. allowing free access of oxygen to the remaining portion of the burner surface; c. and varying the amount of surface from which the oxygen is excluded to thereby achieve a desired amount of heat from that part of the burner surface to which the oxygen has free access. 